Bevel-protractor



C. STRAUB.

BEVEL PROTRACTOR.

APPLICATION man oEc. 23. 1920.

Patented oct 4, 1921.

i UNITED STATES PATENT OFFICE.

CHARLES' STRAUB, or CHICAGO, ILLINOIS.

BEVEL-PROTRACTOR.

To all whom t may concern f Be it known that I, CHARLES; STRAUB, citizen Vof the United States, residingat Chicago, Illinois, have invented certain new and useful. Improvements in a Bevel-Prot-ractor; and I do hereby declare the following Yto be a full, clean-and exact description of the invention, such aswill enable others skilled in the art to which it appertainsto make and use the same.

My invention relates to bevel protractors and in its general aspects aims-to provide a bevel protractor for the use of machinists, draftsmen and the like, which protractor will afford decided advantages over the types heretofore in use. It also aims to provide a simple, compact and easily manipulated protra'ctor which can be used with equal facility for a wide variety of work.

More particularly, my invention aims to provide a bevel protractor having a sliding arm and aims to provide single means for locking the arm both against sliding and against rotation withrespect to the Vback or main member of the protractor. It also aims to provide a dial arranged so thatfit Acan be read equally well from Va number ofy points, and Yto provide an exact peripheral angle permitting the speedy laying out of angles of 45 degrees or 135 degrees. `More over, -my invention aims to provide an inde-V pendently adjustable auxiliary blade so positioned that it can readily be'used either in connection with one edge of the protractor or inrcombination with the dial and the sliding blade for determining angles,l and preferably aims to provide this auxiliary blade or arm in a convenient position for use in checking the grinding of long tapers, such as those on lathed centers or on worm thread tools. Still further and more detailedv objects will appear from the` following specification and from the accompanying. drawings, in which drawings- V lFigure 1 is a plan view of a protractor embodying my invention and showing both of the blades in positionfor use.

n Fig. 2 is an elevation of the same.

Fig. 3 is a transverse section through the same protractor, taken centrally of the dial and along the correspondingly numbered line of Fig. l.

Fig. 4 isa section taken along the VVcorrespondingly numbered line in Fig. 1 to show the mounting ofthe auxiliary blade.V

In the illustrated embodiment, the proi Specification of Letters Patent;

Application led December 23, 1920. Serial No. 432,753.

raeemedoet. 4, 1921'.

tractor of my invention hasl a back or base portion 1, desirably of hardenedsteel, which back desirably includesa raised rim 2 surrounding the movable dial of the protractor, and a wing or arm 3 extendingsubsestantially tangential of the rim. nSeated within the raised rim 1 is a dial 4, which dial preferably is thicker than the height ofk the rim 2 and preferably has a bevel edge ,5 extending somewhat below the top of the Vinsure an accurate fitting of these parts while permitting the dial to rotate freely about this hub vwhen the protractor is to be adjusted. To lock the protractor inany desired position, I ldesirably provide a washer 7 under the knob 8- of a vscrew 9 which is threadedinto the hub 6, the washer being of such size that it partly overlaps the dial 4 and will. be clamped directly against a por- Y tion of the dial whenA the screw 9 is tightened by turning the knobS. j

The face of the dial 4 has a groove which extends substantially tangential ofthe hub 6 andalsorpartly extendsunder the washer .7, .so asto afford a guideway for receiving the main blade 10 of the protractor. This blade is of such a thickness that it will also readily be clamped by the washer 7, so that the single operation of turning the knob 8 will lock the dial against rotating and will clamp the blade 10 against sliding upon 'the dial. Consequently, Ireduce the number of movements necessary for lsuch purposes during the adjusting, and also reduce the expense of manufacture, as it has heretofore been necessary to employ separate provisions'for locking the dial andfor clamping the blade in a longitudinally adjustedl position. 1

To cooperate with the blade indetermining the angles` I desirably provide the arm or wing 3 with a lower straight edge 11 forming an extension of one edgeof the rim 2, and also preferably provide the rim with an adjacent edge 12 disposed at an angle of exactly 135 degrees to the said straight edge '11.y Then I equip the rim 2 with indicating markings A, B and. C respectively spaced byr 9,0 degrees about the common axis of the hub and the dial, and equip the dial with a vsuitable marking for cooperating with the said marks on the rim in indicating the degrees to which the dial has been turned from anygiven starting point. ranged, it will be obvious that the position of the blade l0 can readily be iead with respect to the edge il, and that the marks on the rimean be used, interchangeably so as tol make each one available even when one oi the vothers is concealed by the blade.

To further yincrease the usefulness otmy .protractor at only a/trifiing addition to its cost, I desirably provide an auxiliary blade 13 pivotedto the arm'f von a screw 17 liav-V 'ing va nut .14, this auxiliary vbladeY being adapted to be swung about its pivot to varions positions -with respect to the edge 1l and vtobe locked in position by 'turning the knob 14:. I Yalso desirably recess the arm 3 under the blade 18 so thatftliis arm Vcan be swung' toA protect it against damage and to permit a more compact storing of my protractor.

lhen thus swung toits inoperative position,y the auxiliary bladev 13 engages a-ledge 15 which fornisfa stop 'for this blade and which laffords a mechanical protection for'it when the protractor isfolded` up orstorage. This ledge 175 preferably has its end 16 so disposed that it will actas astop for limiting the outward swinging ot the`anx iliary .blade to a position in which the latter hasits longitudinal edges exactly at right angles to the straightedge 1l` of the main arm ofthe protractor', or at angles` of `'135 degrees to' the edge l2. The ydotted lines showV the armin this position.. I :Thus arranged, it will be obvious that the auxiliary blade lf3' can readily be remployed `Vfor 4transferring.'angles and for` other purposes, both with or without the cooperation of the blade 10,- so that am able to secure iin/'unusually wide range oif adaptability .in

'al quite simple, easily manipulated and compact instrument andin one which invloves no great'difliculties of'manufacture. However, while I have killustrated and described my invention in a lhighly desirable embodiment, I do not wish tol be limited to the particular details ot construction and arrangement here disclosed, since numerous variations might obviously be inade'without devparting from the spirito'if my invention or from tlieappended claims.

I claini as my invention Y 1. In a protractor, abase member having a fixed hub with a threaded opening'therein *zandV anA annular recess' surrounding Ysaid rlhus ar- 1 fixed hub, a graduated dial disposed in the recess and journaled on the hub and'having a groove across its face adjacent to the hub,

a blade slidable in the said groove, a washer concentric with the hub and having opposite edge portions respectively overlapping parts ot' the blade ot the dial, and means engaging the vthreachid opening in the hub for clamping the washer against the said over-A hung parts.

2. Ina protractor, a

en the base member, a blade slidablyinouiited on the dial, a' washer-having different portions contiguonsto and overlapping portions ot the dial andthe blade, anda screw threaded into thel l ase nieinberrand having its head engagingthe washer to clamp the latter against the said portions overlapped byit. i

3.4 In a protractor, a base Amember having two outer straight edges at an angle ,et

degrees to each other and haif'ing anannnli Y recess in its face tl ere being inoL markings on the base outwardly of the said recess and relatively V-at right .angles to eachl :other about the axis oftherecessn a graduated dial rotatably mounted in the recessn a blade slidbase member havingf a straight edfre.y a gaiduated dial rotatableV ably mounted oii-the dial and projecting -beyond the dialyand common means Vfor locking thehdlal against rotjton and for preventing the blade .ii-oni' slit ing on the dial'.

` In afprotractor a base member haa/'ing a circular portion )with ani annularl recess in its face and Vhaving` a stringht-edged:arm tangential toihe circular portion, a. dialfro- .t'at'abiy moinited in the said recess, a blade carried by. the dial and pr i .cting beyond Vthe dialrthere being vcoopera ing markings onthe dial and base inen'iber tor indicating the angle or' the bla-de withrespect `to the straight edge oi" Vthe saidV arnia means-tor locking the dial against` rotation', an auxiliary blade pivoted to thev saidl arm, and

CHARLES 

